1. Field of the Invention
The present invention relates to a broadband wireless communication system using multiple bands. More particularly, the present invention relates to an apparatus and a method for reducing power consumption of a Mobile Station (MS) in the broadband wireless communication system using the multiple bands.
2. Description of the Related Art
In accordance with advances of wireless communication systems, various types and high quality of services provided by the wireless communication systems are demanded. To meet those demands, a broadband wireless communication system is drawing attention. As available frequency resources in the wireless communication system are limited, available frequency bands in the broadband wireless communication system are also limited. To offer a broadband service, the available frequency bands needs to increase.
FIGS. 1A and 1B are diagrams illustrating simplified structures for supporting a single frequency band and a simplified structure for supporting two frequency bands in a conventional wireless communication system.
In the wireless communication system, more particularly, in the broadband wireless communication system represented by the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, a Base Station (BS) operates one Frequency Assignment (FA) or two or more FAs. The BS offers a radio communication service to a Mobile Station (MS) through its FA.
Referring to FIG. 1A, an MS 100 may migrate from an FA1 region 120 to an FA2 region 140. Herein, the FA1 region 120 is a service coverage area where the MS 100 uses the radio communication service using an FA1, and the FA2 region 140 is a service coverage area where the MS 100 uses the radio communication service using an FA2. When the MS 100 traveling in the FA1 region 120 may operate only one FA or when the FA1 and the FA2 are managed by different BSs, the MS 100 hands over between the FAs and uses the radio communication service using the FA2.
Referring to FIG. 1B, when an MS 150 may operate two or more FAs or when two or more FAs are managed by the single BS, the MS 150 may use the radio communication service in both of the FA1 region 160 and the FA2 region 180. As such, when transmitting and receiving signals over the multiple frequency bands, the MS and the BS may send mass data at a high data rate.
As discussed above, by use of the multiple frequency bands at the same time, the system may offer the high-capacity services at a high data rate. However, currently, there is no band use control procedure for effective utilization of the multiple frequency bands. As a result, it is not possible to regulate the bands adaptively used based on a resource usage rate and a channel condition, and use of a secondary FA increases power consumption of the MS.